1. Field of the Invention
The present invention relates to a plasma display panel used for displaying images of television, computer and other apparatuses.
2. Description of Related Art
An example of a plasma display panel of the prior art will be described below with reference to FIG. 7 which is a partially cutaway perspective view of an AC type plasma display panel.
The plasma display panel is configured such that a front substrate includes a transparent first insulating substrate 51, a plurality of pairs of stripe-shaped scanning electrodes 52 and sustaining electrodes 53, a dielectric layer 54, and a protection layer 55 formed in this order. A rear substrate includes a second insulating substrate 56, a plurality of stripe-shaped data electrodes 57 extending perpendicular to the scanning electrodes 52 and the sustaining electrodes 53, and strip-shaped ribs 59 formed on the second insulating substrate 56 forming a plurality of discharge spaces therebetween. The front and rear substrate are formed one upon another. The scanning electrodes 52 and the sustaining electrodes 53 include stripe-shaped transparent electrodes 52a, 53a that are electrically conductive, and conductive layers 52b, 53b, respectively. The conductive layer formed on the transparent electrode is in the shape of a stripe having a smaller width than the transparent electrode, and contains silver. Metals such as copper and chromium can be employed instead of silver in the conductive layer, as is disclosed in U.S. Pat. No. 3,943,007.
A discharge space 58 is filled with a discharge gas including at least one kind of rare gas chosen from helium, neon, argon, krypton and xenon. When the panel is used for color display, a phosphor 60 (only a part of which is shown) is formed to extend over the data electrodes 57 to the side face of the ribs 59.
Now the operation of the AC type plasma display panel of the prior art will be described below.
In a sustaining period of a drive operation, a pulse voltage is applied alternately between the scanning electrodes 52 and the sustaining electrodes 53 so that a sustaining discharge is generated in the discharge space 58 by an electric field generated between the surface of the protection layer 55 on the dielectric layer 54 over the scanning electrodes 52 and the surface of the protection layer 55 on the dielectric layer 54 over the sustaining electrodes 53, to thereby produce an image with visible light generated by the sustaining discharge. To provide a color display, the phosphor 60 is excited by ultraviolet rays emitted by the sustaining discharge and an image is produced by using visible light emitted by the phosphor 60.
On the other hand, in an addressing period of a drive operation, a pulse voltage is applied between the data electrodes 57 and the scanning electrodes 52 or the sustaining electrodes 53 in order to generate an addressing discharge.
In any case, the panel is configured to allow the image to be viewed from the front substrate side of the panel.
A method for forming the scanning electrodes 52, the sustaining electrodes 53, the dielectric layer 54 and the protection layer 55 on the first insulating substrate 51 will be described below taking reference to FIG. 8 which shows a cross sectional view along a projected line in FIG. 7.
In FIG. 8, stripe-shaped transparent electrodes 52a, 53a made of an electrically conductive material such as tin oxide (SnO2) or indium tin oxide (ITO) are formed on the transparent first insulating substrate 51 which, with silver paste printed thereon, is dried and fired to thereby make stripe-shaped conductive layers 52b, 53b that include silver. The entire surface of this substrate is coated with glass paste which is dried and fired to thereby make the vitrified dielectric layer 54, which is further covered by the protection layer 55 formed by vapor deposition of manganese oxide (go).
However, the conductive layers 52b, 53b of this panel have high reflectivity of the surface because the conductive layers 52b, 53b contain silver which is added to improve conductivity. Consequently, extraneous light is reflected on the surface of the conductive layers 52b, 53b as indicated by a solid line in FIG. 8, resulting in a problem of significantly low contrast of the display.